The Brown gene dilutes eumelanin (black pigment) to brown but does not affect phaeomelanin (red/yellow pigment).
Phenotype: Black pigment (if present) is diluted to brown; red/yellow dogs have brown noses and brown foot pads.
Mode of Inheritance:Autosomal recessive
Alleles: B = Full color, b = Brown
Breeds appropriate for testing: Many breeds
Explanation of Results:
Dogs with B/B genotype are expected to express undiluted black pigment. They cannot transmit this brown variant to any of their offspring.
Dogs with B/b genotype are expected to express undiluted black pigment and are carriers of brown. They will transmit the brown allele to 50% of their offspring.
Dogs with b/b genotype are expected to express diluted black pigment. Black pigment (if present) is diluted to brown; red/yellow dogs have brown noses and foot pads. These dogs will transmit the brown allele to all of their offspring.
$45 one test per animal
$65 two tests for coat color/fur type/bobtail (same animal) (excludes Cocoa)
$85 three tests for coat color/fur type/bobtail (same animal) (excludes Cocoa)
+ $15 each additional test if ordering more than three coat color/fur type/bobtail tests on the same animal (excludes Cocoa)
$115 per animal
Additional coat colors $15 per test (excludes Cocoa)
The Brown gene (TYRP1), also called the B Locus, is responsible for brown versus black coat colors in dogs as well as many other mammals. In dogs, five different variants have been identified that contribute to brown. The VGL tests for the three most common found across breeds and uses the combination of the genotypes at each of these variants to define the alleles present. We report these as the dominant (B) and the recessive brown (b). Two copies of brown (b/b) are needed to change the appearance of eumelanin (black pigment) to brown in both hair follicles and skin. TYRP1 does not affect phaeomelanin (red/yellow pigment).
A dog must be homozygous for brown (b/b) and able to produce eumelanin (at least one copy of the E allele at MC1R) in order to express a liver/brown/chocolate phenotype. Because red or yellow dogs that are e/e at MC1R produce only phaeomelanin in their hair follicles, their coat color is not affected by the brown allele. However, two copies of brown (b/b) will change nose and foot pads from black to brown, even in e/e dogs with red or yellow coats.
Recently a variant in another gene was identified to cause the "non-testable chocolate" in French Bulldogs, known as cocoa.
Note regarding French Bulldogs: The dark chocolate color of French Bulldogs will not be detected by the brown gene test. For a test to detect the brown color specific to French Bulldogs, see Cocoa.